Heat exchanger



March 1957 D. w. CHRISTENSEN 2,783,980

HEAT EXCHANGER Filed Dec. 8, 1953 1' n u. m T

7 I Mi 4 v INVENTOR.

ATTORNEY.

of an expansion ring United tates HEAT EXCHANGER Donald W. Christensen,Radiator Company, Wisconsin Racine, Wis., assignor to Young Racine,Wis., a corporation of This invention relates to heat exchangers,particularly of the type where the core unit comprising a battery oftubes supported in parallel relationship on spaced header plates andintermediate baflies, is encased in a shell. Such an exchanger is oftenknown as a converter cooler for use in cooling the oil required in theoperation of heavy automative equipment, as, for example, buses andtrucks.

End sleeve fittings, for attachment to the shell, are provided withports for connection in oil and coolant conduits to permit their flowthrough the tubes and labyrinth of the core to elfect the required heattransfer.

In order to seal off the oil flow through the tubes from the labyrintharound them within the shell, it is imperative to have the core-unitheader-plates bonded to the shell. The bonding is usually brazing,effected by induction or torch flame heating a silver solder alloypositioned concentric with the junction of the header plates and thesleeves mounted on the shell. Where, as heretofore generally has beenthe case, these header plates are comparatively light, thin metal thereis a very imited areaof contact between the header plates and thesleeve. Since the strength of brazed joints is conditioned upon the areaof contact between the metals involved, joints formed with theabove-noted header plates per se are often rather weak, subjecting theheat exchangers of this type and use to the hazard of easy fracture andsubsequent leakage.

The main objects of this invention, therefore, are to provide animproved form of header-plate and shellsleeve joint which will permit ofa stronger bond than heretofore obtainable; to provide an improved formof joint forunits of this kind which materially increases the area ofthe'bonding surfaces intermediate the coreunit header-plates and theembracing shell-sleeve; and to providean improved form and arrangementof the parts between which the bond is formed and which permits animproved method of assembling the parts preparatory to their beingbonded.

In the accompanying drawings,

Fig..1 is aperspectiveview,partly broken away to show the interior, of aconventional heat exchanger of the above-noted type and embodying thisinvention;

Fig. 2 is an enlarged fragmentary, exploded perspective of oneheader-plate and ring forming a part of this invention;

Fig. 3 is an enlarged, fragmentary, sectional view showing the relativepositions of the several parts of the assembly incident to placing thering on the core-unit header-plate, and

Fig. 4 is a similar view showing the parts in their bonded assembledpositions.

The essential concept of this invention involves a pair of telescopingmembers one of which is in the form embraceable over and seatable on aheader plate and the other is in the form of a sleeve which supports thering and is telescopically supported on the housing shell.

A conventional heat exchanger, of the above-noted converter type, forembodiment in which this invention has been devised, comprises in themain a core unit 5 and supporting shell 6, equipped with end fittingshaving ports for connecting the exchanger in the respective conduits forthe fluid and coolant between which heat transfer is to be effected.

The core unit 5, for exchangers of this type, generally is formed of abundle of thin-wall tubes 7 supported in spaced parallel relationship ona pair of headers 8. The

ends of the tubes 7 are bonded to the header plates 8. Baflles 9 ofappropriate number and form, are arranged in axiallly-spaced position onthe tubes 7.

- The shell 6, generally a casting, mounts at each end fittings in theform of sleeve members 10 and attachable end caps 11. The sleeve members10 are formed with ports 12 and the end caps 11 have axial openings 13which respectively permit the exchanger to be interposed in the fluid(oil) and coolant conduits to effect heat transfer flows through thetubes 7 and the labyrinth surrounding suoh tubes.

In order to fluid-seal the labyrinth flow against communication with theflow through the tubes it is imperative to bond the header plates 8 ofthe core unit 5 within the sleeve members 10. These header plates 8,being rather thin metal, it will be obvious that by the conventionalpractice of bonding the header plates directly to the sleeve members 10,the bonding area is extremely limited. This, of necessity, constitutes:a rather fragile joint which, under the rough usage to which someautomotive vehicles are often subjected, makes for easy fracture. Theconsequence of such fracture is a leakage of the fluid and/or coolantbetween the labyrinth and the tubes, with a resultant loss in efiiciencyin the heat exchanger operation, if not its complete ineffectiveness.

The herein disclosed embodiment of this improved header-plate-shelljoint, in its simplest form, comprises providing a ring 14 dimensionedand recessed to embrace and seat a header plate 8 and telescopicallyfitted within a suitably recessed sleeve member 10.

The ring 14 may be of almost any so as to permit expansion thereof toset itself on the header plate 8. The ring 14 is of a thickness severaltimes greater than the thickness of the associated header plate 8' andimparts a substantial peripheral rigidity thereto. Preferably, the innerface of the ring ld is formed with a groove or recess 15, substantiallyas thick as the header plate 8, to provide a seat for the perimeter ofthe header plate 8, as shown in Figs. 3 and 4.

The sleeve 10, of which there would be a pair for each heat exchanger,preferably is a casting. It is dimensioned internally to slide snuglyover one end of the shell 6. As here shown, the sleeve, one for each endof the shell 6, has the outer end enlarged to provide a flange l6Whereto is attached one of the appropriate end caps 11, in the usualmanner. Inwardly of the flange 16, the sleeve 10 is formed with anannular recess 17 extending axially inward a short distance from theface of the flange 16. The internal diameter of this recess is equal tothe external diameter of the ring 14 when encircling and seating theheader plate 8. "The header plate 8, in this instance, is substantiallyequal to the inside diameter of the sleeve 10, inwardly of the sleeverecess 17, and hence substantially equal to the outside diameter of theshell whereon the sleeve 10 is telescoped.

When the core unit 5 and shell 6 have been duly assembled, by the methodhereinafter set forth, and each of the sleeves is positioned on theshell, as shown in Fig. 4, each ring 14 is sweat bonded to therespective header plate 8 and to the respective sleeve 10, as indicatedby the exaggerated black areas around the abutting faces of these parts,as shown in Fig.4. At its opposite end each form of split ring embraceand firmly Patented Mar. 5, 1957 avsasso sleeve 10 is also bonded to theshell 6, as indicated by the black areas in Fig. 4.

This bonding is done in the conventional manner. With the assembledparts standing on end and with rings of silver solder alloy laid aroundthe corners where the heavy back fillets appear in Fig. 4, either byinduction orby conventional torch flame the solder rings are melted.Well known capillary action draws the molten silver solder alloy inbetween the contacting faces of the ring 14 and the header plate 8 andthe sleeve 10 and also forms fillets in the corners constituted by theadjacent right angle faces of these 'partsas shown by the excessivelyblack portions in Fig. 4.

An improved method of assembly is practiced for the aforesaidconstruction and relative arrangement of the rings 14 and sleeves 10.After the rings 14 and sleeves 10 have been duly constructed, thatimproved method involves substantially the following steps:

1. The requisite baffies 9, placed on 4 or 6 tubes 7 with the usualspacers, are suitably secured together and the assembly inserted intothe shell 6;

2. This preliminary assembly is then stood on end, whereupon all of thetubes 7 are inserted into the baflles 9 and the requisite header plates8 are setover and bonded to the ends of the tubes 7, in the conventionalmanner, to

complete the core unit 5;

3. One sleeve 10 is then slipped over the respective end of the shell 6and after proper positioning on the shell is bonded thereto, as shown inFig. 3,

4. The core unit 5 is then shifted axially of shell 6 to so expose oneheader plate 8 as to permit a ring 14 to be expanded and placed over theheader plate 8, the perimeter of the plate becoming seated in the ringrecess 15, as shown in Figs. 3 and 4;

5. The core unit 5 is then shifted back into the shell 6 to locate thering 14 properly in the sleeve recess 17, as shown in Fig. 4;

6. The ring 14 is then brazed to the header plate 8 and to the sleeve10, in the manner hereinbefore explained;

7. The other sleeve 10 is then placed on the other end of the shell 6and shoved inwardly a sufficient distance to so expose the other headerplate 8 as to permit a ring 14 to be expanded and placed around theplate 8, as explained above;

8. With the second ring 14 in place, the second sleeve 10 is pulledoutwardly on the shell '6 to properly position the header-plate-ringassembly in the sleeve recess 17;

9. So positioned, the second sleeve 10 is thereupon bonded to the shell6 and to the ring-header plate assembly, as hereinbefore explained,preferably in that order.

As will be noted from Fig. 4, a consequence of using this form andarrangement of parts is the obtaining of a very considerable surfacearea of bonding between the header plates 8 and the sleeves 10. Thatarea is many times greater than has been obtained heretofore with theconventional practice of bonding the header-plates 8 directly to thesleeve or shell. Such a joint, as that herein disclosed, is, indeed, sorigid as to practically remove all hazard of fracture even under themost extraordinary conditions occurring in the use of automotivevehicles equipped with oil converters embodying this invention.

It will be understood, of course, that certain variations andmodifications of this particular embodiment may be made withoutdeparting from the spirit of this invention as defined in the followingclaim.

I claim:

A heat exchanger embodying a shell and a core unit permanently bondedtogether to form an integrated and inseparable assembly, t e shellcomprising a tubular intermediate element and a pair of sleevestelescopically received on and metallically bonded to the opposite endsof the intermediate element whereby the shell is of a predeterminedover-all axial length, the sleeves each having a short annular recessextending inwardly from the outer end thereof and the remainder of eachsleeve having a uniform smaller bore therethrough of substantially thesame diameter as the outer surface of said intermediate element wherebyat least one of said sleeves may initially be slid inwardly along saidintermediate member to fully expose an associated end of saidintermediate member, the core unit comprising a pair of thin rolledmetal header plates spanned by a plurality of tubes the ends of whichtubes are bonded to the respective header plates whereby the core unithas an over-all axial length less than the overall axial length of theshell so that the header plates are disposed wholly within the annularrecesses in the outer ends of said sleeves, each header plate being of adiameter slightly less than the diameter of its associated sleeve recesswhereby to present an annular space around each header plate whenreceived within its associated sleeve, and a ring embracing each of theheader plates and filling the aforementioned annular space andtelescopically contacting the respective sleeves within the annularrecesses, each ring having an annular circumferential groove in theinner surface thereof receiving the periphery of its associated headerplate and each ring being of a thickness several times greater than thethickness of said header plates and being metallically bonded to therespective header plates and sleeves.

References Cited in the file of this patent UNITED STATES PATENTS1,289,350 Zimmerman Dec. 31, 1918 1,599,370 Muhleisen Sept. 7, 19261,994,779 McNeal Mar. 19, 1935 2,061,980 Price Nov. 24, 1936 2,083,679Adams June 15, 1937 2,202,494 Jacocks May 28, 1940 2,298,996 Woods Oct.13, 1942 2,512,748 Lucke June 27, 1950 FOREIGN PATENTS 314,261 GermanySept. 5, 1919

